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NEED Mission Statement
The mission of The NEED Project is to promote an energy conscious and educated society by creating effective networks of students, educators, business, government and community leaders to design and deliver objective, multisided energy education programs.
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Energy Data Used in NEED Materials
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Baseload Balance
Table of Contents
Standards Correlation Information 4
Materials 5
Elementary Baseload Balance
Teacher Guide 6
Teacher Cheat Sheet 9
Balance Placards 10
Peak Demand and Generation Cards 11
Baseload Balance
Teacher Guide 12
Student Infosheet 15
Load and Generation Parameters 17
Hang Tag Cards 18
Incident Cards 24
Teacher Cheat Sheet 25
Student Worksheet 26 Evaluation Form 27
Standards Correlation Information
www.NEED.org/educators/curriculum-correlations/
Next Generation Science Standards
This guide effectively supports many Next Generation Science Standards. This material can satisfy performance expectations, science and engineering practices, disciplinary core ideas, and cross-cutting concepts within your required curriculum. For more details on these correlations, please visit NEED’s curriculum correlations website.
Common Core State Standards
This guide has been correlated to the Common Core State Standards in both language arts and mathematics. These correlations are broken down by grade level and guide title, and can be downloaded as a spreadsheet from the NEED curriculum correlations website.
Individual State Science Standards
This guide has been correlated to each state’s individual science standards. These correlations are broken down by grade level and guide title, and can be downloaded as a spreadsheet from the NEED website.
Materials
ACTIVITY MATERIALS NEEDED
Elementary Baseload Balance
Double pan balance
Weights sets or plastic building bricks
Clock
Plastic box or bowl
Cardstock or construction paper
Baseload Balance
Tape
Scissors
String
Colored paper or cardstock
Marker boards
Dry-erase markers & erasers
Rope (optional)
Elementary Baseload Balance
TEACHER GUIDE
A more thorough demonstration of this activity is played out in the original Baseload Balance, recommended for grades 6-12. See page 12 for more information.
Grade Levels
Primary, grades 2-5, with guidance Elementary, grades 3-5 Time 45-60 minutes
Additional Resources
This activity utilizes electricity and energy use vocabulary. For additional background information on energy sources, electricity, generation, and transmission, check out these NEED resources at shop.NEED.org. Elementary Energy Infobook Coal guides Hydropower guides Oil and Natural Gas guides
Solar guides
Wind guides Reliably Smart
&Background
Most students don’t give electric power much thought until the power goes out. Electricity plays a giant role in our day-to-day lives. This activity demonstrates how electricity supply is adjusted to meet the demands of consumers. It also encourages students to explore the differences between baseload and peak demand power, as well as the ways energy source cost and availability factor into the decisions made in power generation. After students have explored meeting demand with supply of power, the concept of storage for renewables is introduced in a second round of play.
In each round, you will lead your students through a hypothetical day, consisting of morning, all day, evening, and night. As the time of the day changes, students are encouraged to think about how their energy use changes. Brass or plastic weight sets or plastic building bricks are used to represent power demand or power generation, and you can adjust the activity according to the age and abilities of your students. Some groups may be able to self-direct in this activity and determine the mass in grams or the number of plastic bricks to use, and others will need your guidance and direction. A simple double-pan balance is used to show how demand for electricity is balanced with generation by electric power producers.
Objectives
Students will be able to explain how demand for electricity changes throughout the day.
Students will be able to list energy sources used for baseload generation and those that can be used for peak demand.
Students will be able to explain why storage, in combination with some renewable energy sources, is a good option to incorporate into electricity generation planning.
Materials
Double-pan balance
Gram weight set OR plastic building bricks
Clock
Plastic box or bowl
Cheat Sheet, page 9
Balance Placards Master, page 10
Peak Demand and Generation Cards Master, page 11
2Preparation
In this activity, a five-gram weight will represent 5 MW of load or generation. If your weight set has enough pieces to accommodate this activity, use it. If not, collect enough plastic building bricks, using a scale in which one brick is equal to 5 MW of load or generation (two bricks of the same size equal 10 MW). Consult the Cheat Sheet to see how many you will need. If you use building bricks, you may want to designate one color for generation and one color for demand. If you teach younger students and decide to use bricks, you might assemble brick sets representing the different amounts of load or generation as described in the Procedure. Use a dry-erase marker to label them.
Copy the Balance Placards. Cut them apart and fold them on the dotted line to make tent-style labels that stand up.
Copy and cut apart the Peak Demand and Generation Cards.
Designate one student to be the timekeeper. That student will be responsible for indicating the time on the demonstration clock as you move through the activity.
Procedure
PART ONE – WITHOUT STORAGE
1. Start by explaining what demand, load, generation, baseload, and peak mean in this activity. Demand describes the amount of electricity consumed at any time. Load is the amount of electricity we pull from the grid. Generation is the amount of electricity that power plants produce. Baseload or base generation refers to electricity consumption or generation at all times of the day or night all year long. Peak demand or generation refers to electricity consumption or generation that varies at different times of the day or night, and different times during the year. For example, hospitals use power all day and all night, and coal-fired power plants generate power all day and night. However, we may use air conditioning only during the warmer months and usually more in the afternoon and evening than in the morning. Some energy sources, like solar and wind, are able to produce power only at certain times of the day. Some energy sources, like hydropower and natural gas, can be used as baseload generation and can increase their generation to meet peak demand.
2. Distribute the Peak Demand or Generation cards to students. Hand them as many weights or bricks as they need or have them calculate what they need, depending on age and ability.
3. Place the balance on the table in front of you. Place the “Demand” card on one side of the balance such that students can read the word. Place the “Generation” card on the other side of the balance in a similar fashion.
4. Say, “All day and all night, we use electricity. Our refrigerators run, hospitals take care of people, and factories produce goods.” Place 115 MW worth of bricks or weights in the Demand pan. The balance will tip to the Demand side.
5. Say, “All day and all night, power plants produce electricity. Coal, natural gas, hydropower, and nuclear power plants run all day and all night, generating electricity.” Place 115 MW worth of bricks or weights in the Generation pan. The pans should now be balanced.
6. Say, “See how the two pans are balanced? Electric utility companies are careful to make only as much electricity as we will use. If they produce more electricity than needed, the energy is wasted and cannot be stored in most situations. If they don’t produce enough, some things we need will not be able to work correctly.”
7. Instruct the timekeeper to set the clock to read 7:00. Say, “It is now 7:00 in the morning, and people are getting up to start their day. Who has the Morning Peak Demand?” As this student comes to the table with the balance, ask students to think of things they use in the morning that need electricity. Answers may include things like a coffee maker, toaster, lights in the bathroom, or an electric toothbrush. When the Morning Peak Demand student places the weights or bricks in the pan, the balance should tip toward Demand.
8. Say, “What will the power company do now?” Allow students a moment to think about what should be done. Allow them to see the card the Morning Peak Demand student had and know how much demand was placed on the system. Ask students to come to a consensus about what peak power source(s) should be utilized to balance the scale.
9. The student(s) with the power source(s) to meet morning demand should place their weights or bricks in the Generation pan. The pans should now be balanced.
10. Say, “Utilities try to make sure they spend as little as possible while meeting demand. This way they don’t have to bill customers even more in the future. How much money did it cost to meet the morning demand? Do you wish to change the sources you used? If so, what should we use and why?” Allow students some time to discuss this and come to a consensus, adjusting the Generation pan as appropriate.
11. Say, “Some things are turned on and run all day long, like lights at a school or computers at a business. Who has All-Day Demand?” As this student comes to the front, ask students to think of things that we use during the day that use electricity. Answers may include things like television, computers, and any machines at school. The All-Day Demand student should place the correct number of weights or bricks in the Demand pan.
12. Say, “What will the power company do now?” Allow students a moment to think about and come to a consensus about what should be done. Remind them to consider the cost of their choice. Students should add Generation weights or bricks to balance the pans.
13. Instruct the time keeper to move the clock to 5:00. Say, “It’s now 5:00 and the end of the day. School is over, offices are closing, and people are going home for the day. What do we need to do to the Demand pan?” Allow students to think about what should be done and come to a consensus.
14. As students remove the Morning Peak demand and perhaps the All-Day Demand weights or bricks from the Demand side of the balance, the balance will tip toward the Generation pan.
15. Use your hand to equilibrate the balance so it’s even on both sides. Say, “Are there any other adjustments we need to make? Does someone have a card that says, Evening Peak Demand?” As that student comes forward, ask students to think of things that might be used in the evening but not during the day. Ask students to guess whether evening demand would be less than, the same as, or greater than demand during the day. As the Evening Peak Demand student lays the appropriate weights or bricks in the Demand pan, hold the balance steady until students decide how demand will shift in the evening. Then remove your hand, allowing the balance to equilibrate.
16. Say, “What about generation? What will happen to the source(s) you have chosen to use to generate power during the day?” If students have chosen solar power, they will need to remove that from the generation side of the balance and replace it with something else. They may or may not need to add or subtract generation depending on what they did with the all-day demand.
17. Instruct the timekeeper to move the clock to read 11:00. Finally, say, “It is now 11:00 pm, and everyone is in bed or will be in bed very soon. We are back to baseload demand and baseload generation.” Remove all of the Peak Demand weights or bricks, and remove excess Generation weights or bricks, returning to the same amount you started with at steps 4-5.
18. Discuss with students how demand and generation changed throughout the day. Ask them how they think it changes from one month to the next, or how different seasons affect the demand and generation of electricity.
PART TWO – WITH STORAGE
1. Collect the Demand and Generation cards and their associated weights or bricks from students. If you’d like, assign a different student to be the timekeeper.
2. Replace the first Solar Generation card, valued at 10 MW, with a Solar Generation card valued at 25 MW. If and when solar is used, they must put the full 25 MW on the Generation side of the balance. Distribute the appropriate mass or or number of bricks.
3. Replace the first Wind Generation card, valued at 10 MW, with a Wind Generation card valued at 15 MW. When students decide to use wind generation, they must use the full 15 MW. Distribute the appropriate mass or number of bricks.
4. Replace the first Evening Peak Demand card, valued at 15 MW, with an Evening Peak Demand card valued at 35 MW. This will simulate peak demand in the hottest part of the summer when air conditioners are taxing the grid. Distribute the appropriate mass or number of bricks.
5. Explain to students that in reality, some renewable resources, like solar and wind, produce more power than is necessarily needed at that time of day. Solar Generation is at its highest generation midday, but the demand for electricity is not at its highest point at the same time. Wind generation is at its highest late in the evening, but people do not always use as much power at that time.
6. Explain that adding some way of storing the excess energy will ensure that it is available when peak demand is at its highest, which is the late afternoon and evening during the hottest parts of the summer.
7. Set the plastic box or bowl in front of the balance. Place the Storage placard in front of it. Explain that the bowl represents ways of storing electricity for use later when the demand is highest. If age-appropriate, go into further detail about some options available for storing electrical power, such as pumped storage or battery storage systems.
8. Redistribute the Demand and Generation cards and their associated bricks.
9. Explain to students that you are going to run through the activity again, but this time if a renewable resource is producing more power than needed, the excess energy (bricks) will be placed in storage (the bowl or box). Later in the activity, if more power is needed than is being produced, bricks from the bowl or box can be added to the generation side of the balance to meet the demand.
10. Run the activity again, allowing students to come to a consensus every time a decision must be made.
Extensions
Have students keep a daily log of devices that are turned on and off throughout the day. They should list the time of day something is turned on and something is turned off. Discuss these lists and see how they compare to the changing demand in this activity. As a class, decide how you might update this activity to reflect your class’s energy use.
Invite a representative from your utility company to talk to your class about managing demand for electricity and how the utility keeps up with changing consumer demand.
Ask a local utility or business to bring an electric vehicle (EV) to your class or talk about their EV fleet.
Elementary Baseload Balance
CHEAT SHEET
Demand and Generation Equivalents
MW Equivalent Total mass of weights Bricks needed
5 1 gram 1 2x2 10 2 grams 1 2x4 15 3 grams 1 2x2, 1 2x4 20 4 grams 2 2x4 25 5 grams 1 2x2, 2 2x4 30 6 grams 3 2x4 35 7 grams 1 2x2, 3 2x4 40 8 grams 4 2x4 45 9 grams 1 2x2, 4 2x4 50 10 grams 5 2x4 55 11 grams 1 2x2, 5 2x4 60 12 grams 6 2x4 65 13 grams 1 2x2, 6 2x4 70 14 grams 7 2x4 75 15 grams 1 2x2, 7 2x4 80 16 grams 8 2x4 85 17 grams 1 2x2, 8 2x4 90 18 grams 9 2x4 95 19 grams 1 2x2, 9 2x4 100 20 grams 10 2x4 105 21 grams 1 2x2, 10 2x4 110 22 grams 11 2x4 115 23 grams 1 2x2, 11 2x4
Demand and Generation Amounts
Part One – Without Storage
Time of Day
Demand Generation Required
Baseload (all day, all night) 115 MW 115 MW Morning 20 MW 20 MW All day 15 MW 15 MW Evening 15 MW 15 MW
*NOTE: Baseload remains on the balance throughout the activity. Morning, all day, and evening are added and removed according to the time during the activity, and whether students consider the all-day activities to be included with evening. The maximum demand or generation that should be on the balance during Part One is 150 MW.
Part Two – With Storage
Time of Day
Demand Generation Storage
Baseload (all day, all night) 115 MW 115 MW 0 MW Morning – with solar only 20 MW 35 MW 15 MW Morning – without solar 20 MW 20 MW 0 MW All day – with solar 15 MW 30 MW 15 MW All day – without solar 15 MW 15 MW 0 MW Evening 35 MW 20 MW 0 MW
** Students may decide that solar comes online in the morning, or they may decide it comes online at the “all-day” time period. Thus, both scenarios are given here. Either way, when solar comes online, 15 MW of power go into storage that can be used in the evening.
Elementary Baseload Balance
Demand Generation Storage
Elementary Baseload Balance
PEAK DEMAND AND GENERATION CARDS
Morning Peak Demand, 20 MW Natural Gas Peak Generation, 10 MW, $150, any time All-Day Peak Demand, 15 MW Wind Generation, 10 MW, $45, evening only
Evening Peak Demand, 15 MW Solar Generation, 10 MW, $75, daytime only
Natural Gas Peak Generation, 10 MW, $90, any time Hydropower Peak Generation, 5 MW, $50, any time
Natural Gas Peak Generation, 5 MW, $90, any time
Hydropower Peak Generation, 10 MW, $60, any time
Solar Generation, 25 MW, $75, daytime only
Wind Generation, 15 MW, $45, evening only
Evening Peak Demand, 35 MW
Baseload Balance
TEACHER GUIDE
A simplified version of this activity, Elementary Baseload Balance, utilizes a double pan balance and weight set or building blocks. This version is recommended for elementary students but can be utilized with younger or older students as needed as a great demonstration and discussion starter. See page 6 for more details.
Grade Levels
Intermediate, grades 6-8
Secondary, grades 9-12
Time
1-2 class periods, depending upon the depth and number of rounds
Additional Resources
This activity utilizes electricity and energy use vocabulary. For additional background information on energy sources, electricity, generation, and transmission, check out these NEED resources at shop.NEED.org.
Intermediate Energy Infobook
Secondary Energy Infobook
Coal guides
Hydropower guides
Oil and Natural Gas guides
Nuclear guides
&Background
Most students don’t give electric power much thought until the power goes out. Electricity plays a giant role in our day-to-day lives. This activity demonstrates how electricity supply is transmitted on the electric grid to consumers. It also encourages students to explore the differences between baseload and peak demand power, and how power companies maintain supply to ensure customers have power as they need it.
Students will be introduced to the economics of electricity generation and supply and be able to see firsthand the financial challenges utilities must overcome to be able to provide the power demanded by consumers at the lowest cost. Figures, costs, and sources used in this activity are roughly based on current industry uses and costs but have been made into round figures for ease of implementation. In this simulation, students assume roles as “loads” or “generation.” Students will progress through several “rounds,” attempting first to balance, and then adding more challenges or components as they progress.
Objectives
Students will be able to differentiate between baseload and peak demand power.
Students will be able to explain the purpose of using a variety of sources to meet base and peak load power demand.
Students will be able to describe the challenges of using certain sources to meet base and peak load power demand.
Students will be able to describe how energy storage can be incorporated into demand management and how it can be beneficial for supporting renewables.
Materials
Individual marker boards with erasers and markers
Baseload Balance Student Infosheet, pages 15-16
2Preparation
Reliably Smart
Load and Generation Parameters master, page 17
Hang Tag Cards, pages 18-23
Incident Cards, page 24
Cheat Sheet, page 25
Baseload Balance Student Worksheet, page 26
Familiarize yourself with the activity instructions and student background information before facilitating the game with students.
Make a copy of the Cheat Sheet for yourself.
Copy the hang tags and cut them apart. Attach the tags to four colors of paper or color the cards so that the generation, transmission, load, and storage cards are each a different color. Laminate, if desired, for future use.
Make a copy of the Incident Cards. Cut the cards apart and fold on the dotted line. Laminate, if desired, for future use.
Make a copy of the Student Worksheet and Student Infosheet for each student.
Prepare a copy of the Load and Generation Parameters master to project for discussion.
Designate an area of the room to be the Regional Transmission Organization (RTO). On one side of this area will be the generation group, and the other side will be the load group. Each side should have its own marker board, eraser, and marker.
Decide if a student will be the RTO leader, or if the teacher or another adult will assume this role. Having a student assume this position will create a more student-centered activity. Depending on the ability of the students in your group, using a student for this role may require more monitoring and time than if a teacher is in charge.
Instruct all students to read the infosheet prior to the activity.
Student Roles
Baseload demand – 3 students Peak load demand – 8 students Baseload generation – 8 students Peak load generation – 8 students Transmission – 3-5 students RTO – 1-3 students or a teacher Storage – 1-5 students (optional)
A Vocabulary SPECIFIC TO THE GAME
Baseload Generation Load Transmission Peak demand Megawatt
NOTE: If your class size is smaller, you may elect to use “proxy” baseload demand cards and generator cards that are not assigned to students but sit “online” at all times.
Procedure
1. Assign each student a role that corresponds to each hang tag. If your class does not have enough students for each tag, the baseload tags can be tied to the rope because they are always in operation. A list of the roles can also be found above. The transmission roles are best assigned to students who are able to think quickly on their feet and have good math skills. Storage roles can be assigned after playing rounds one and two. If you do not have enough students to fill all required and optional roles, some baseload or storage roles can be “proxies” that are tied online as needed.
2. Allow time for students to research their roles and reread the background information. Students should be familiar with the vocabulary and information on their hang tags, including generating capacity, energy source, and power demand. Depending on the level of your students, you may choose to have them skip the section of the background information that discusses regional transmission organizations and independent system operators.
3. Project the Load and Generation Parameters master for the class. Discuss the relative cost for each source and plant type as well as the suggested reasoning for the cost of each. Explain that the cost figures are whole, round numbers for easy game play, and that realistically, costs are less round and can be more variable, depending on a number of factors. Discuss the Student Worksheet and explain how students should fill in the tables during the simulation. You may elect to have all students complete it during the simulation as they engage in their roles. Or you may choose to have unassigned students complete it and share the data with the class.
4. The activity begins with the transmission students gathering in the Regional Transmission Organization area, each holding onto the rope or string. The student on each end should have plenty of available rope or string onto which the generation students and load students will attach. These students will decide which peak load providers (plants) will be brought online to meet increasing demand as the activity progresses. They will also help the RTO by tabulating the current load or generation on their side of the line. They will display it on their marker board and update it as the activity progresses.
5. In the generation group, the residential baseload, commercial baseload, heavy industry baseload, and all baseload generation students all hold ends of the rope on their respective sides. They will be holding onto the rope during the entire activity because as baseload power or generation, they are providing or using power all the time.
6. At the appropriate time indicated on each hang tag, each load student will join the grid, increasing the load demand. Residential demand comes up (online) at about 7:00 a.m. as people begin to wake. Demand continues to rise as more residential, commercial, and industry come on the grid, pulling electricity or creating another load.
7. The transmission students will need to balance the generation against the load. They will choose the best generation students to come online to balance the load students. The RTO can monitor or assist the transmission group by announcing the time and reminding each load or role when to join. Be sure to pay attention to intermittent renewables, like solar, being online at the same time when the sun may not be up.
8. After going through the activity once (one complete 24-hour period), reset the activity to early morning and run through a second round, balancing the generation against the load, while now using the cheapest available sources to run for the longest amount of time. You may also wish to reassign students to different roles depending on their command of the activity in the first round.
9. Run a third round, resetting as needed and incorporating storage as a new way to manage demand. Select one of the incident cards to set the stage for using storage.
10. Run a fourth round. RTOs usually require generation to be 15 percent above demand. Play the game again, accounting for the prescribed demand plus the additional 15 percent. Hold a class discussion about why this extra generation is required.
Discussion and Research
Roughly what time was the peak demand? When is the least amount of power needed?
Why did we choose our particular sources we did when balancing generation and demand?
How would knowledge of historical data and weather forecasts help in making decisions about which sources to use?
How did storage make the balancing easier/harder? What challenges would there be if using storage types like those in the game? What factors were not addressed in our game play?
What do you think the costs of the various storage types might be? How might that impact their use in tandem with renewable energy?
In addition to hourly changes in demand for electricity, there are seasonal differences in demand. Research these seasonal differences and explore reasons for a greater demand for electricity at different seasons of the year.
It is projected that the number of electric vehicles and hybrid electric vehicles in the U.S. will increase dramatically over the next decade. What impact do you think this will have on the demand for electricity? How might we adjust to any changes in demand?
The Coronavirus Pandemic of 2020 brought many changes. Businesses, industry, and schools closed for a period of time. People worked from home and left home less often. Explore the impact of the pandemic on the demand for electricity. Was there a change in the total demand for electricity? Was there a shift in the time of day that peak demands occurred? Will there be any lasting impacts on the demand for electricity, and how might the electrical generation industry react to any potential changes?
Extension
Ask students to write a persuasive letter in support of a certain type of power plant after playing the game. Letters should include information gleaned about the plant’s advantages and disadvantages, as well as the feasibility for use in generation of electricity at the lowest cost.
Baseload Balance
STUDENT INFOSHEET
Introduction
Four kinds of power plants produce most of the electricity in the United States: coal, natural gas, nuclear, and hydropower. Natural gas produces roughly 40 percent of the electricity we use, while nuclear and coal plants generate about 19 percent. There are also wind, geothermal, waste-to-energy, solar, and petroleum power plants, which together generate about ten percent of the electricity produced in the United States. All of this electricity is transmitted to customers, or loads, via the network of transmission lines we call the grid.
Wind Farms
Utility-scale wind turbines are often grouped together into what is called a wind farm. These turbines convert motion energy in the wind directly into electrical energy or electricity. Wind is among the fastest growing sources for electricity in the U.S. and across the globe. Wind turbines can be located on land or at sea. Wind turbines produce no emissions. Wind can sometimes be intermittent and may not always be available.
Solar Facilities
Solar power can be generated using photovoltaic (PV) arrays, often called solar panels. These facilities can be located in open fields, above parking lots, and on the surface of building structures. Solar power can also be generated by focusing the sun’s light on a reflective surface that reflects back onto a container storing fluid or molten materials. This material is then used to create steam to turn a turbine. In these instances, Concentrating Solar Power (CSP) is also considered a thermal power plant. CSP and PV technologies combine to make solar one of the fastest growing sources for electricity across the globe.
Fossil Fuel Power Plants
Fossil fuel plants burn coal, natural gas, or petroleum to produce electricity. These energy sources are called fossil fuels because they were formed from the remains of ancient sea plants and animals. Most of our electricity comes from fossil fuel plants in the form of coal and natural gas.
Power plants burn the fossil fuels and use the heat to boil water into steam. The steam is channeled through a pipe at high pressure to spin a turbine generator to make electricity. Fossil fuel power plants produce emissions and contribute to global climate change. The amount and type of emissions can vary based upon the type of fossil fuel and technologies used within the plant. Fossil fuel plants are sometimes called thermal power plants because they use heat energy to make electricity.
Nuclear Power Plants
Nuclear power plants are called thermal power plants, too. They produce electricity in much the same way as fossil fuel plants, except that the fuel they use is uranium, which isn’t burned. Uranium is
a mineral found in rocks underground. Uranium atoms are split to make smaller atoms in a process called fission that produces enormous amounts of thermal energy. The thermal energy is used to turn water into steam, which drives a turbine generator. Nuclear power plants do not produce carbon dioxide emissions, but their waste is radioactive. Nuclear waste must be stored carefully to prevent contamination of people and the environment.
Hydropower Plants
Hydropower plants use the energy in moving water to generate electricity. Fast-moving water is used to spin the blades of a turbine generator. Hydropower is called a renewable energy source because it is renewed by rainfall.
Waste-to-Energy (Biomass) Plants
Waste-to-energy facilities are thermal power plants that burn garbage and other waste to produce electricity. The heat from the incinerator creates steam in a boiler that drives a turbine generator. Facilities monitor and scrub their emissions and recycle ash to be environmentally friendly.
Cost of Electricity
The cost for generating electricity depends on several factors.
Fuel Cost
The major cost of generating electricity is the cost of the fuel. There are also other factors that tie into the cost of a fuel, including production cost, manufacturing or refining costs, cost of transporting the fuel, and more.
Building Cost
Another factor is the cost of building the power plant itself. A plant may be very expensive to build, but the low cost of the fuel can make the electricity economical to produce. Nuclear power plants, for example, are very expensive to build, but their fuel—uranium— is inexpensive.
Combined Cycle vs. Simple Cycle
In the most simple of thermal power plants, a fuel is burned and water is heated to form high-pressure steam. That steam is used to turn a single turbine. Thermal power plants running in this manner are about 35 percent efficient, meaning 35 percent of the energy in the fuel is actually transformed into useable electrical energy. The other 65 percent is “lost” to the surrounding environment as thermal energy.
Combined cycle power plants add a second turbine in the cycle, increasing the efficiency of the power plant to as much as 60 percent. By doing this, some of the energy that was being wasted to the environment is now being used to generate useful electricity.
Efficiency
When figuring cost, you must also consider a plant’s efficiency. Efficiency is the amount of useful energy you get out of a system. A totally efficient machine would change all the energy put in it into useful work. Changing one form of energy into another always involves a loss of usable energy. Efficiency of a power plant does not take into account the energy lost in production or transportation, only the energy lost in the generation of electricity.
In general, today’s power plants use three units of fuel to produce one unit of electricity. Most of the lost energy is waste heat. You can see this waste heat in the great clouds of steam pouring out of giant cooling towers on some power plants. For example, a typical coal plant burns about 4,500 tons of coal each day. The chemical energy in about two-thirds of the coal (3,000 tons) is lost as it is converted first to thermal energy, and then to motion energy, and finally into electrical energy. This degree of efficiency is mirrored in most types of power plants. Thermal power plants typically have between a 3040% efficiency rating. Wind is usually around the same range, with solar often falling below the 30% mark. The most efficient plant is a hydropower plant, which can operate with an efficiency of up to 95%.
Meeting Demand
We don’t use electricity at the same rate at all times during the day. There is a certain amount of power that we need all the time called baseload power. It is the minimum amount of electricity that is needed 24 hours a day, 7 days a week, and is provided by a power company. However, during the day at different times, and depending on the weather, the amount of power that we use increases by different amounts. We use more power during the week than on the weekends for offices and schools. We use more electricity during the summer than the winter because we need to keep our buildings cool. An increase in demand during specific times of the day or year is called peak demand. This peak demand represents the additional power above baseload power that a power company must be able to produce when needed.
Power plants can be used to meet baseload power, or peak demand, or both. Some power plants require a lot of time to be brought online — operating and producing power at full capacity. Others can be brought online and shut down fairly quickly.
Coal and nuclear power plants are slow, requiring 24 hours or more to reach full generating capacity, so they are used for baseload power generation. Natural gas is increasing in use for baseload generation because it is widely available, low in cost, can quickly reach full generating capacity, and is a cleaner-burning fuel.
Wind, hydropower, and solar can all be used to meet baseload capacity when the energy source is available. Wind is often best at night and drops down in its production just as the sun is rising. Offshore wind is more consistent. Solar power is not available at night, and is greatly diminished on cloudy days. Hydropower can produce electricity as long as there is enough water flow, which can be decreased in times of drought.
To meet peak demand, energy sources other than coal and uranium must be used. Natural gas is a good nonrenewable source to meet peak demand because it requires only 30 minutes to go from total shutdown to full capacity. Many hydropower stations have additional capacity using pumped storage. Some electricity is used to pump water into a storage tank or reservoir, where it can be released at a
later time to generate additional electricity as needed. Pumped storage hydropower can be brought fully online in as little as five minutes.
Some power plants, because of regulations or agreements with utilities, suppliers, etc., do not run at full capacity or year-round. These power plants may produce as little as 50 percent of maximum generating capacity but can increase their output if demand rises, supply from another source is suddenly reduced, or an emergency occurs.
Making Decisions
Someone needs to decide when, which, and how many additional generating locations need to be brought online when demand for electricity increases. This is the job of the Regional Transmission Organization (RTO) or Independent System Organization (ISO). RTOs and ISOs work together with generation facilities and transmission systems across many locations, matching generation to the load immediately so that supply and demand for electricity are balanced. The grid operators predict load and schedule generation to make sure that enough generation and backup power are available in case demand rises or a power plant or power line is lost.
Transmission Organizations
Besides making decisions about generation, RTOs and ISOs also manage markets for wholesale electricity. Participants can buy and sell electricity from a day early to immediately, as needed. These markets give electricity suppliers more options for meeting consumer needs for power at the lowest possible cost.
Several RTOs operate bulk electric power systems across much of North America. More than half of the electricity produced is managed by RTOs, with the rest under the jurisdiction of individual utilities or utility holding companies.
In the 1990s, the Federal Energy Regulatory Commission introduced a policy designed to increase competitive generation by requiring open access to transmission. Northeastern RTOs developed out of coordinated utility operations already in place. RTOs in other locations grew to meet new policies providing for open transmission access. Members of RTOs include the following: independent power generators; transmission companies; load-serving entities; integrated utilities that combine generation, transmission, and distribution functions; and other entities such as power marketers and energy traders.
RTOs monitor power supply, demand, and other factors such as weather and historical data. This information is input into complex software that optimizes for the best combination of generation and load. They then post large amounts of price data for thousands of locations on the system at time intervals as short as five minutes.
The Continental U.S. Electric Grid
Baseload Balance INCIDENT CARDS
INCIDENT
At 3:00 p.m. heavy cloud cover moves over the region, taking out your solar generation. If you can’t provide enough power to meet the load, RTO must choose who will lose power and be in blackout. How could a blackout have been avoided?
INCIDENT
At 2:00 p.m. a baseload coal unit trips, and you lose 10 MWs of baseload coal. If you can’t provide enough power to meet the load, RTO must choose who will lose power and be in blackout. How could a blackout have been avoided?
INCIDENT
At 5:00 p.m. a derecho hits, damaging power lines. You lose half your commercial and residential load. You must balance your load with generation. Could this have been predicted?
AVAILABLE GENERATION
TIME TIME
BASELOAD GENERATION ONLINE OFFLINE COAL BASELOAD 40 MW $50/MW NATURAL GAS BASELOAD 20 MW $30/MW NUCLEAR BASELOAD 50 MW $30/MW HYDROPOWER BASELOAD 5 MW $30/MW SOLAR BASELOAD 5 MW $40/MW WIND BASELOAD 5 MW $40/MW NATURAL GAS BASELOAD 15 MW $40/MW WASTE-TO-ENERGY BASELOAD 10 MW $60/MW
TIME TIME
PEAK GENERATION
NATURAL GAS SIMPLE CYCLE 5 MW $250/MW 30 MIN NATURAL GAS SIMPLE CYCLE 10 MW $90/MW 30 MIN NATURAL GAS SIMPLE CYCLE 5 MW $90/MW 30 MIN NATURAL GAS SIMPLE CYCLE 10 MW $150/MW 30 MIN NATURAL GAS SIMPLE CYCLE 5 MW $200/MW 30 MIN
ONLINE OFFLINE
BASELOAD GENERATION
COAL BASELOAD 40 MW $50/MW
NATURAL GAS BASELOAD 20 MW $30/MW
NUCLEAR BASELOAD 50 MW $30/MW HYDROPOWER BASELOAD 5 MW $30/MW SOLAR BASELOAD 5 MW $40/MW
WIND BASELOAD 5 MW $40/MW NATURAL GAS BASELOAD 15 MW $40/MW WASTE-TO-ENERGY BASELOAD 10 MW $60/MW
PEAK GENERATION
NATURAL GAS SIMPLE CYCLE 5 MW $250/MW 30 MIN
NATURAL GAS SIMPLE CYCLE 10 MW $90/MW 30 MIN
NATURAL GAS SIMPLE CYCLE 5 MW $90/MW 30 MIN
NATURAL GAS SIMPLE CYCLE 10 MW $150/MW 30 MIN
NATURAL GAS SIMPLE CYCLE 5 MW $200/MW 30 MIN
HYDROPOWER PEAK 10 MW $70/MW 5 MIN
HYDROPOWER PEAK 5 MW $50/MW 5 MIN
HYDROPOWER PEAK 10 MW $90/MW 5 MIN
TIME TIME
ONLINE OFFLINE
TIME TIME
ONLINE OFFLINE
Baseload Balance Evaluation Form
State: ___________ Grade Level: ___________ Number of Students: __________
1. Did you conduct the entire unit? Yes No 2. Were the instructions clear and easy to follow? Yes No 3. Did the activities meet your academic objectives? Yes No 4. Were the activities age appropriate? Yes No 5. Were the allotted times sufficient to conduct the activities? Yes No 6. Were the activities easy to use? Yes No 7. Was the preparation required acceptable for the activities? Yes No 8. Were the students interested and motivated? Yes No 9. Was the energy knowledge content age appropriate? Yes No
10. Would you teach this unit again? Yes No Please explain any ‘no’ statement below.
How would you rate the unit overall? excellent good fair poor
How would your students rate the unit overall? excellent good fair poor
What would make the unit more useful to you?
Other Comments:
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